Elevated production of 20-HETE in the cerebral vasculature contributes to severity of ischemic stroke and oxidative stress in spontaneously hypertensive rats.
Hypertension is a major risk factor for stroke, but the factors that contribute to the increased incidence and severity of ischemic stroke in hypertension remain to be determined. 20-hydroxyeicosatetraenoic acid (20-HETE) has been reported to be a potent constrictor of cerebral arteries, and inhibitors of 20-HETE formation reduce infarct size following cerebral ischemia. The present study examined whether elevated production of 20-HETE in the cerebral vasculature could contribute to the larger infarct size previously reported after transient middle cerebral artery occlusion (MCAO) in hypertensive strains of rat [spontaneously hypertensive rat (SHR) and spontaneously hypertensive stroke-prone rat (SHRSP)]. The synthesis of 20-HETE in the cerebral vasculature of SHRSP measured by liquid chromatography-tandem mass spectrometry was about twice that seen in Wistar-Kyoto (WKY) rats. This was associated with the elevated expression of cytochrome P-450 (CYP)4A protein and CYP4A1 and CYP4A8 mRNA. Infarct volume after transient MCAO was greater in SHRSP (36+/-4% of hemisphere volume) than in SHR (19+/-5%) or WKY rats (5+/-2%). This was associated with a significantly greater reduction in regional cerebral blood flow (rCBF) in SHR and SHRSP than in WKY rats during the ischemic period (78% vs. 62%). In WKY rats, rCBF returned to 75% of control following reperfusion. In contrast, SHR and SHRSP exhibited a large (166+/-18% of baseline) and sustained (1 h) postischemic hyperperfusion. Acute blockade of the synthesis of 20-HETE with N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016; 1 mg/kg) reduced infarct size by 59% in SHR and 87% in SHRSP. HET0016 had no effect on the fall in rCBF during MCAO but eliminated the hyperemic response. HET0016 also attenuated vascular O2*- formation and restored endothelium-dependent dilation in cerebral arteries of SHRSP. These results indicate the production of 20-HETE is elevated in the cerebral vasculature of SHRSP and contributes to oxidative stress, endothelial dysfunction, and the enhanced sensitivity to ischemic stroke in this hypertensive model.
Dunn
Kathryn M
KM
Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Renic
Marija
M
Flasch
Averia K
AK
Harder
David R
DR
Falck
John
J
Roman
Richard J
RJ
D000578:Amidines / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000187:drug effects; D042926:Cytochrome P-450 CYP4A / Q000378:metabolism; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D006973:Hypertension / Q000150:complications* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D020244:Infarction, Middle Cerebral Artery / Q000150:complications* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D018384:Oxidative Stress; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017382:Reactive Oxygen Species / Q000378:metabolism; D012720:Severity of Illness Index; D020521:Stroke / Q000209:etiology* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D013997:Time Factors; D015854:Up-Regulation
D000578:Amidines; D004791:Enzyme Inhibitors; C000708209:HET0016; D006893:Hydroxyeicosatetraenoic Acids; D007527:Isoenzymes; D017382:Reactive Oxygen Species; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D042926:Cytochrome P-450 CYP4A